Little is known about the incidence of and associated management outcomes of occult hemothorax in blunt trauma patients. The increased use of computed thoracic tomography for the evaluation of the multiply injured blunt trauma patient has led to an increase in the identification of these hemothoraces and management dilemmas.A retrospective review of blunt trauma patients with occult hemothoraces was performed. Patients were divided into 2 groups: chest tube versus no chest tube. Outcomes and complications for the 2 groups were defined. Data included demographics, Injury Severity Score, length of stay, need for mechanical ventilation and thoracic consult, pneumonia, and empyema. The size of the occult hemothorax was measured on the computed thoracic tomography.Eighty-eight patients (21.4%) had a total of 107 occult hemothoraces. Patients in the chest tube group were more likely to have a higher Injury Severity Score and an associated occult pneumothorax and to have smaller hemothoraces.Occult pneumothoraces occur in a significant proportion of the multiply injured blunt trauma population. Small, isolated, occult hemothoraces can be managed safely in the stable patient.